Jewel-cupping machine.



No. 886,310. PATENTED APR. 23, 1908.

J. WBNNSTROM.

JEWEL GUPPING MACHINE. APVPLIGATION FILED MAR. 29, 1906.

'MWIGJ'SES; I lime/22w"? Brooklyn,

r FFTQE JOHN WENNniROM OF BROOKLYMNEW YORK, ASSIGNOR TO THE AMERICAN CUPPED DIAMOND 00., A CORPORATION OF MAINE.

JEWEL-CUPPING MACHINE.

Specification of Letters Patent. Application filed March 29, 1906. Serial No. 308,699.

Patented April 28, 190%.

To cit: whom it concern:

Be it known thatI, JOHN WENNsTRoM, of county of Kings, State of New York, have invented an Improvement in Jewel-Cupping Machines, of which the following description, in connection ,with the accompanying drawings, is a specification,

like characters on the drawings representing like parts.

This invention relates to a machine which is adapted to form a. cup or recess in an 8X- tremely hard substance, particularly a diamond, so that it may be used as a step bear ing for electric meters and similar purposes.

A diamond has a sort of grain, as does wood, and the direction in which this grain runs must be taken into consideration in grinding or cutting a diamond, if this work is to be done to the best. advantage. In other words a diamond can be out only with the greatest difficulty, if at all, when the grindmg surface moves over the diamond in some having a bed directions, while it may be cut with comparative case if thegrinding surface moves over the diamond in a particular direction. In forming a cavity in a diamond which would render the same suitable for a step hearing, it is essential that the surface of the cavity or cup be perfectly smooth and rounded, in order that friction may be minimized.

My invention has for its object to provide a form of grinding machine which is espe' cially adapted to form, in a diamond or other hard jewel, a spherical-shaped cavity or cup, the surface of which shall be perfectly smooth.

A further object is to provide a machine of this character which is adapted to enable the operator to cause the grinding device to operate upon the work to the best advantage, and with facility.

I accom lish' these, and other advanta; geous resulls, by the means shown in the accompanying drawing, in which,

Figure 1 is a side elevation of a grinding machine provided with my invention. Fig.

2 is an end view, and Fig. 3 is a plan ,view.

thereof. Figs. 4 and 5 are detail, longitudinal sectional views of the chuck, showing the work in semilinished and finished condition respectively,-and Fig. 6 is a detail sectional view of the grinding head.

The grindim machine comprises a base a on which is mounted a head stock 0, in which a horizontal shaft (Z is j ournaled, said shaft being provided With a pulley e by means of which it may be driven. A spindle f'is removably secured to the front end of the shaft d, and a grinding head 9 is mounted in said spindle. Said grinding head 9 is preferably disk-shaped having its edge rounded or curved transversely about the central point inthe disk :that is, the head is substantially represented by the zone of a sphere, the central plane of which intersects the center of the sphere. This head is preferably made of soft cast iron, for reasons which will hereafter appear. A tail stock h is also mounted on the bed 7) and a flat, rear-. wardly and horizontally projecting table i is rigidly secured to said tail stock.

A holder 7c rests on and is pivotally mounted by means of a boltj on the flat horizontal surface of the table t, said bolt j being so lo-- cated that the said holder swings about a vertical axis, a continuation of which intersects the center of the head 9, and therefore the axis of the shaft (i at right angles. A chuck, which comprises a straight rod we having a centrally;disposed work-receiving 'recess or cavit r m in one end is mounted to ally in twoslide longitudinally and horizon" u ri hts if intc 'ral with holder in such a position that the longitudinal center line of said rod intersects the center of the grinding head 9, and consequently the point of intersection of the axes of shaft (1 and'of holder 71:. Springs 'n are each connected at one end to an upright/t", and at their other ends to a bar 0, which is adapted to engage the-rear end of the chuck rod m to press the same towards the grinding head. An adjusting screw 0 is preferably provided in the bar 0, which is adapted directly to engage the end of rod m, so that by turning this screw the tension of the springs may be varied, and consequently the force with which the chuck is forced towards the head 9 will'be correspondingly varied. An arm 39 is adjustably connected to rod m by means of a set screw p, and a fixed guide rod g is mounted, on the rear standard 7t" and passes through the arinp, so that said rod m is held from turning while being free to reciprocate as above described.

In preparing the stone-for cupping it is customary to set'thesame on the end of a steel billet, or wire, as 'r, by brazing or by other means, so that the jewel Will be held thereon with the greatest rigidity. See Figs. 4 and 5. As the rough diamondthus secured to the steel billet is very irregular, it is necessary that a face be provided thereon, which is at ri ht angles to the billet in which the cup is to be formed, as shown in Fig. 4. This face is readily formed by pressing the end of the billet against a flat polishing wheel. In performing this operation the billet is turned until the position is found in which the diamond may be ground to the best advantage. That is, the direction of the grain of 1c diamond is ascertained and then the end. of the billet is marked accordingly. These billets r are cut off in short lengths, and are adapted to fit tightly in recess m of the chuck m. I

A vertical shaft t is suitably mounted in the rear of the bed I), saidshaft having a crank-arm u and a driving ulley 12 mounted thereon. A connecting rod or link to is pivotally connected at one end to the holder 7c, and at its other end to the crank arm a by means of a crank in u, said crank-pin being adjustable in a ove-tail slot u formedin and extending longitudinall of the crankarm throughout its entire length. It will be a parent that when the shaft t is rotated the older is will be oscillated, the amplitude of its oscillations obviously depending on the position to which the crank-pin u is adjusted with reference to the axis of shaft t.

To set the diamond holding billet 'r in the chuck, it is usually more convenient to remove the rod m from its su port, this being done by simply lifting the bar 0 out of engag'ement therewith and drawing it out of Y the sup orting uprights k. The billet is then tig tly set in such a position in the chuck that the grindinghead will act on the diamond the correct way of the grain, or to the best advantage, when the chuck has been replaced. The chuck rod m having been placed in position in the uprights It, and the sprirags. n and bar 0 having been readjusted, t e iamond s will be pressed against the grinding head 9, andthe shafts d and 12 will be rotated, causing the head 9 to be rotated and the chuck m to be oscillated about the pivot bolt 3', the portion-of the face of the diamond which. engages the head 9 thus being moved in an are having as its center the center of the curved face of the head. This face of the head g is supplied with a mixture of oil and diamond dust, and the latter becomes embedded in the pores of the cast-iron of which said head is composed, so that the diamond dust acts to grind the diamond and form a cup or cavity therein. The cup thus formed, however, would be rough or have. grooves or scratches running across it in the direction of the path of rotation of the head 9 if the diamond were held stationary, but, as the latter is oscillated transversely of said path while the grinding operation is taking place, the

whole surface engaged is ground evenly, so that the surface of the spherical shaped cavity or on which is'formed in the iamond is perfectly smooth and highly polished.

I have found that with different diamonds the amplitude of the oscillations may be varied to advantage, although I prefer to have the oscillations ofsuificient lengthto cause the diamond to engage the face of head 9 throughout its entire width, so that an annular groove will not be formed in said face of the head,cbut said face will always ,be kept in the form of a sphere or zone.

While the direction of the grain of the stone will ordinarily be found in facin it, so that when it is-first placed inthe mac 'ne it will be ground to the best advantage by the head 9, yet if it is'found on examination,

after the grinding operation has been carried on for a suitable length of time, that the I bar 0, so that this force may be quickly varied.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

I 1. In a grinding machine, a rotatable grinding head, a work holder, a rod rotatably mounted in said holder and longitudinally .movable therein to and from said head, said rod having a chuck in its end next the head, and means for locking said rod in different positions of rotation, said means permitting said longitudinal movement of said rod, sub stantially as described.

2. In a grinding machine, a rotatable grinding head, a chuck mounted to rotate about and move longitudinally of an axis which intersects the axis of said head at an angle, and means for locking said chuck in different positions of rotation which permitsaid longitudinal movement thereof, su bstantially' as described. 1 3. In a grinding machine, a rotatabl grinding head, a chuck holder, a rod having a chuck in one end and mounted to rotate, and to move longitudinally in said holder towards said ,head, an arm rotatably conthe diamond is forced nected to said rod and extending transversely thereof, means for locking said arm on said rod, and means engaging said arm for holdmg it from swinging movement about said head, a chuck mounted on said holder, and

rod and permitting longitudinal movement of the rod While the arm is locked thereon, substantially as described. I

4. In a on grinding machine, a rotatable, curved-faced grinding head, a bed, a chuckholder pivoted thereon and movable about an axis which intersects the center of said flat bearing surface extending transversel of said holder s axis for supporting said hol iler in the different oscillatory positions thereof, substantially as described.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnesses.

JOHN WENNSTROM.

movable in a line intersecting said center, I Witnesses: means v for automatically oscillating said L. H. HARRIMAN, holder about its said axis, said bed having a H. B. DAVIS. 

